Calderite

Calderite is a mineral in the garnet group with the chemical formula (Mn2+,Ca)3(Fe3+,Al)2(SiO4)3.

It is dark reddish brown to dark yellowish in color and generally granular massive in form.[1]

It was named for geologist James Calder who worked on the geology of India. The name was first applied to a rock in manganese deposits in Katkamsandi, Hazaribagh district, Bihar and at Netra, Balaghat district, Madhya Pradesh, India. later transferred to its predominant mineral.[1][2] In 1909 it was described as a mineral from Otjosondu, Otjozondjupa Region, Namibia.[3]